Portable computing devices, also referred to as notebook or laptop computers, typically have feet disposed on their bottom surfaces. The feet raise the portable computer off of a supporting surface, such as a desk or table. This may serve several purposes, such as preserving the finish of the bottom surface of the portable computer, or improving cooling of the portable computer, among others. FIG. 1A illustrates a computing device 120, such as a typical portable computer. Portable computing device 120 includes a display housing rotatably coupled to a main housing or enclosure through a hinge. The display housing includes a display screen. The main housing includes a keyboard and a pointing device. Additional aspects of the internal circuitry of a computer such as computing device 120 may be found in U.S. Pat. No. 6,222,549, which is incorporated by reference herein. The main housing includes a base which is the bottom surface of the main housing. A portable computer 120 typically includes four feet 100 disposed on the bottom of an enclosure 106, as illustrated in FIG. 1B. FIG. 1B illustrates a bottom view of the computing device 120 illustrated in FIG. 1A. Each foot 100 is typically positioned at a corner of the bottom surface of an enclosure 106 of the portable computer 120. The foot 100 is part of a foot assembly 110, which includes the foot 100 and a foot socket 104.
FIG. 1C illustrates an exploded view of a prior art foot assembly 110 for a portable computer, such as the computer 120 illustrated in FIG. 1A. Computer 120 includes an internal supporting chassis 108 to which various hardware components of the computer are attached, such as for example a motherboard, memory, and battery. The chassis 108 is typically comprised of a metal or another rigid material. At the point on the chassis 108 where a foot assembly 110 is to be located, the chassis 108 includes an internally threaded screw bore 109 to accommodate a machine screw 102. The screw 102 is fastened through a foot socket 104 into the bore 109 to retain the enclosure 106 to the supporting chassis 108. The enclosure 106, or case, is typically comprised of a rigid material, and houses the components of the computer. The enclosure 106 includes a recessed well 107 to accommodate the socket 104. Once the screw 102 is installed, the head of screw 102 remains exposed within the center portion of the socket 104. To cover the head of screw 102, a foot 100 is installed into the foot socket 104.
FIG. 1D illustrates a perspective view of the prior art foot 100. Foot 100 includes three snaps 150 extending from a cylindrical base 152. The three snaps 150 are positioned radially about the perimeter of the base 152, and are spaced equally from each other. Clearances 101 are positioned between adjacent snaps 150. The snaps 150 are radially symmetrically positioned about the perimeter of the base 152. Foot 100 is radially symmetric about the central axis of base 152. Each snap 150 is attached to the base 152 at a proximal end, and each snap 150 has a substantially wedge shaped cross section. A pawl 153 is an engagement disposed at the distal end of each snap 150 from the base. Pawl 153 includes an edge on the end of each snap 150. Pawl 153 is designed such that when installed into foot socket 104, the pawl 153 catches the snap 150 on the foot socket 104 so as to prevent the foot 100 from disengaging the foot socket 104. FIG. 1E illustrates a top view of the foot 100. FIG. 1F illustrates a cross-sectional side view of the foot 100 taken along the section A-A in FIG. 1E. FIG. 1G illustrates a cross-sectional side view of the foot 100 taken along the section B-B in FIG. 1E.
FIG. 1H illustrates a perspective view of a prior art foot socket 104. Foot socket 104 includes a substantially cylindrical base 111 and a raised center portion 112. Foot socket 104 is radially symmetric about the central axis of base 111. The base 111 is disc shaped, with a bore in the center. The raised center portion 112 has a substantially circular shape, and is coupled to the base 111 by three raised supports 113. The supports 113 are spaced equally about the base 111. The socket 104 is indexed in the well 107 using a ledge 121 so that the socket 104 may only be placed in the well 107 in a single rotational orientation.
FIG. 1I illustrates a top view of the foot socket 104. FIG. 1J illustrates a cross-sectional side view of the foot socket 104 taken along the section A-A in FIG. 1I. FIG. 1K illustrates a cross-sectional side view of the foot socket 104 taken along the section B-B in FIG. 1I. FIG. 1L illustrates a bottom view of the foot socket 104. FIG. 1M illustrates a cross-sectional side view of the foot socket 104 taken along the section C-C in FIG. 1L. The raised center portion 112 includes an aperture 114 to accommodate screw 102. When screw 102 is installed into chassis 108, the head of screw 102 is adjacent to an exterior (or bottom) side 118 of the socket 104, while the interior (or top) side 117 of the socket 104 is adjacent to the surface of well 107 of the enclosure 106. Socket 104 includes three circular cosmetic features 190 on the exterior surface 118 of the base 111. Foot socket 104 includes three undercuts 115 disposed between adjacent supports 113. Undercuts 115 are coupled to the base 111 and extend towards the central axis of the base 111. Undercuts 115 are edges on which pawl 153 catches when foot 100 is installed into the foot socket 104. Foot socket 104 includes three vertical orientation ribs 116. Each vertical rib 116 is disposed on the exterior side 118 of each support 113, and extends along the length of each support 113 between the base 111 and the center portion 112.
The dimensions of the prior art foot 100 are now described. Referring to FIG. 1F, the diameter of base 152 is 8.00 mm with a tolerance of −0.10 mm. The diameter of the snaps 150 about the base 152 is 6.20 mm with a tolerance of −0.10 mm. The angle of pawl 153 is 15.0 degrees from perpendicular of the upper surface of base 152. The overall height of foot 100 from the lower surface of base 152 to the upper surface of the snaps 150 is 3.60 mm. The edge of each snap 150 has a 0.30 mm radius or blend (R0.30) applied to the edge between the upper and side surfaces of the snap 150. The inner diameter between the snaps 150 is 3.00 mm. The diameter of the snaps 150 at pawls 153 is 6.70 mm with a tolerance of ±0.05. The height of pawls 153 from the upper surface of base 152 is 0.96 mm with a tolerance of ±0.05 mm. The height of base 152 is 1.84 mm with a tolerance of ±0.010 mm. Referring to FIG. 1G, the edge of the base 152 a 0.50 mm radius or blend (R0.50) applied to the edge between the upper and side surfaces of the base 152. The foot 100 has a volume of about 115.12 mm3.
The dimensions of the prior art foot socket 104 are now described. Referring to FIG. 1I, arc angle 170 between the center of support 113 and the edge of support 113 is 30 degrees. Arc angle 171 of support 113 is 50 degrees. Arc angle 172 between undercuts 115 is 60 degrees. Arc angle 173 between adjacent supports 113 is 70 degrees with a tolerance of ±0.50 degrees. Referring to FIG. 1J, the height of undercut 115 from the lower surface of base 111 is 1.80 mm with a tolerance of ±0.05 mm. The depth of ledge 121 from support 113 is 0.5 mm with a tolerance of +0.05 mm. Referring to FIG. 1K, the interior surface of the three supports 113 at base 111 are positioned about a diameter of 9.50 mm. The diameter of the center portion 112 is 7.89 mm with a tolerance of −0.05 mm. The diameter of aperture 114 is 2.80 mm. The angle of support 113 is 15 degrees from perpendicular of base 111. The center portion has a depth of 0.80 mm with a tolerance of −0.10 mm. The height of the lower surface of undercut 115 from the lower surface of base 111 is 0.50 mm. The height of the lower surface of undercut 115 from the upper surface of undercut 115 is 0.26 mm. The base 111 is 1.20 mm thick, with a tolerance of ±0.05 mm. The upper surface of center portion 112 is 3.00 mm above the upper surface of base 111, with a tolerance of −0.05 mm. The overall height of socket 104 is 4.20 mm. The outer diameter of the base 111 is 15.00 mm. The inner diameter of base 111 is 8.20 mm with a tolerance of +0.10 mm. The diameter of the outer portion of the three undercuts 115 is 7.56 mm. Referring to FIG. 1L, the angle 175 between cosmetic features 190 is 120 degrees. Referring to FIG. 1M, the depth of cosmetic features 190 is 0.5 mm, and the diameter of the cosmetic feature 190 is 1.7 mm.